Stroke annually affects approximately 180 per 100,000 inhabitants
in the industrialized world; it is the most common cause of persisting
disabilities [1]. Restoration and improvement of independent gait are
major goals of stroke rehabilitation and pivotal for aspired social and
vocational integration.

Currently, a task-specific repetitive approach, i.e., numerous
practices of complex gait cycles, is regarded as the most promising to
restore motor function after stroke [2]. Conventional therapy, including
treadmill training with partial body-weight support (BWS) [3-4], is
limited by the effort to assist the patients' gait, e.g., when
placing the paretic limb. Gait machines intended to relieve therapeutic
effort to assist the patients' gait in combination with
physiotherapy (PT) affected superior gait ability in most stroke trials
[5-8] and a meta-analysis [9]. The machines, offering practice up to
1,000 steps per session, either used an exoskeleton [10-11] or an
end-effector approach [12-13].

Most gait machines restrict themselves to the repetitive practice
of simulated walking on the floor. Stair climbing up and down, however,
is an integral part of everyday mobility both at home and in the
community. A quarter of Berlin's subway stations offer neither an
elevator nor a conveyor [14]. A large Italian cohort study included 437
nonambulatory patients with stroke; only 5 percent of them regained
independent stair climbing following conventional inpatient
rehabilitation [15].

The therapeutic effort needed for relearning stair climbing after
stroke is considerable, especially considering the risk of falls. To
ease therapist effort, a gait robot (G-EO System [Reha Technology AG;
Olten, Switzerland; eo comes from Latin for "I walk") based on
the end-effector principle was designed [16]. The trajectories of the
foot plates and the vertical and horizontal movements of the center of
mass were fully programmable, enabling wheelchair-bound subjects not
only the repetitive practice of simulated floor walking but also up and
down stair climbing. The lower-limb muscle activation patterns of
ambulatory subjects with stroke, recorded during the real and simulated
stair-climbing condition, corresponded with each other [16]. The device
follows the HapticWalker, a research prototype with limited clinical
applicability because of its dimensions and required high voltage, by
applying the same principles of an end-effector device with programmable
footplates [17-18].

This article presents the first clinical results in nonambulatory
patients with subacute stroke allocated to two groups. The patients were
either treated on the G-EO System in combination with PT (experimental
group) or received individual PT (control group) for 4 weeks. The
absolute session durations were comparable, and the PT of both groups
concentrated on restoring gait, including stair climbing. We treated the
two groups consecutively because of the limited availability of the G-EO
System. Our hypothesis was superior gait and stair-climbing ability in
the experimental group at the end of the intervention phase. The data
should help to appraise the feasibility and clinical potential of the
G-EO System.

The first 15 patients formed the experimental group and the second
15 patients formed the control group; i.e., the two groups were treated
consecutively.

Intervention

The experimental group patients had 60 min sessions of individual
PT every workday for 4 weeks, i.e., 20 sessions. Within the first 30
min, they practiced on the G-EO System. This time included donning and
doffing and breaks; the intended net therapy time on the G-EO System
ranged from 15 to 20 min. One therapist, who has 10 years of experience
in machine-supported gait rehabilitation, assisted the patients with
putting on the harness while sitting in their wheelchair, getting onto
the G-EO System in the wheelchair using a ramp from the rear, fixing the
feet on the plates, hoisting the patient, attaching the lateral ropes,
and setting the therapy parameters memorized by the G-EO System
computer. During each session, the patients practiced 5 to 15 min of
simulated floor walking followed by 5 to 10 min of repetitive simulated
stair climbing up and down. The patient practiced a minimum of 300 steps
on the simulated floor and climbed a minimum of 50 steps on the
simulated stair during each session. Breaks were optional, but
uninterrupted training intervals of at least 5 min for simulated floor
walking and 3 min of simulated stair climbing were required. Heart rate
and blood pressure were monitored at the beginning and end of each
session. During the training, the therapist manually assisted knee
extension while standing in front of the patient if needed. The
treatment parameters were noted for each session, and the steps taken
during simulated walking were converted into the distance covered based
on chosen step length.

Another physiotherapist with 8 years of experience in stroke
rehabilitation was responsible for the second 30 min of the session. She
worked with the patients on improving gait and stair climbing in
real-life situations depending on the individual impairment level. She
applied a task-specific repetitive approach in conjunction with
tone-inhibiting maneuvers to practice the motor tasks repetitively.
Technical aids such as walking canes or orthoses could be used. The
meters covered during walking and the numbers of steps climbed were
noted.

The control group received 60 min of PT every workday for 4 weeks,
i.e., 20 sessions, with the same physiotherapist as the experimental
group. Again, she strongly emphasized the restoration and improvement of
gait and stair climbing by applying a task-specific repetitive approach
in conjunction with tone-inhibiting maneuvers (technical aids could be
used). An assistant could help with stair climbing. The meters covered
during walking and the numbers of steps climbed were also noted.

All patients participated in a comprehensive rehabilitation
program. In addition to the individual PT sessions, patients performed
ergometer training on a daily basis, physical therapy (30 min sessions
three times a week, including massage and spa therapy), and occupational
therapy (45 min sessions five times a week). The comprehensive program
is intended to improve the abilities in the basic activities of daily
living (sessions in the early morning to relearn washing and dressing
alternating with sessions during the day to promote upper-limb
recovery). Speech and neuropsychology therapies were administered on an
individual basis. On Saturdays, every patient received two 30 min
sessions, either PT or occupational therapy and physical therapy.

Assessment

The primary variable was the FAC, where 0 = could not walk at all
and 5 = could walk independently anywhere, including climbing up and
down one flight of stairs (8 steps) irrespective of whether in an
alternate or nonalternate pattern (technical aids and a bilateral
handrail could be used) [20].

Secondary variables were the Rivermead Mobility Index (RMI) of 0 to
15, which includes 15 hierarchical items from turning over in bed to
running that the patient could perform (score 1 point) or not (score 0
points) [21]; the 10 m test to assess the mean velocity (meters per
second), where the patient walked 14 m twice at a self-selected speed
and the time on 10 m was taken (an experienced therapist assisted the
patient, if needed, and any applied technical aids were kept constant);
the lower-limb Motricity Index (MI) of 1 to 100, which tested the muscle
strength of ankle dorsiflexion, knee extension, and hip flexion [22];
and lower-limb muscle tone, in which five passive movements (ankle
dorsiflexion, ankle eversion, knee flexion and extension, and hip
flexion) were tested while the patient laid supine using the lower-limb
Resistance to Passive Movement Scale of 0 to 20 [23].

Two experienced therapists blinded to group assignment assessed
patients at study entry ([T.sub.0]), after 2 weeks ([T.sub.2]), after 4
weeks ([T.sub.4]), and at follow-up ([T.sub.F], 3 months after study
end). Because both therapists were team members, knowledge of the group
allocation could not be excluded. The FAC was therefore video-recorded
and rated by an experienced therapist on maternity leave, because she
was blinded to group assignment.

Statistics

In case of a missing value, we performed an intention-to-treat
analysis; i.e., the assessment was carried on and, if not possible, the
last available data was continued. We tested homogeneity between the two
groups at study onset with a Mann-Whitney test (p < 0.05).

In the first step, we calculated absolute changes over time during
the intervention ([T.sub.0] to [T.sub.4]) and during follow-up
([T.sub.0] to [T.sub.F]) and the corresponding 95 percent confidence
interval. In the second step, we assessed between-group differences
using a nonparametric Mann-Whitney test for two independent samples (p
< 0.025, Bonferroni adjustment).

RESULTS

All but one control group patient completed the study (patient did
not complete follow-up) (Figure 1). Table 1 summarizes the demographic
and clinical data of the two patient groups at study onset, which did
not differ. All but one experimental group patient completed the study
(patient stopped G-EO System training after 2 weeks because of knee
arthritis).

The patients rated the G-EO System positively, including the
stair-climbing option; initial fears of overexertion expressed by five
patients receded after the first sessions. The G-EO System's
recorded treatment parameters indicated that the amount of BWS was
continuously reduced and that the net treatment time, training velocity,
and training intensity continuously increased.

[FIGURE 1 OMITTED]

With respect to the training intensity in both groups, Table 2
summarizes the mean meters covered and the mean stairs climbed per
session during the first and second blocks of 10 sessions. The
experimental group patients practiced more intensively; in particular,
the numbers of stairs climbed differed in favor of the experimental
group. Among the 15 control group patients, 11 practiced stair climbing
at least once during the first 2 weeks and 13 practiced during the last
2 weeks. Stair climbing was actually part of 3.3 sessions during the
first 10 sessions and 4.6 sessions during the last 10 sessions.

Over time, patients of both groups improved significantly with
respect to FAC (Figure 2), gait velocity (Figure 3), RMI, and MI (p <
0.05); muscle tone did not change (Table 3). During the intervention,
the experimental group patients improved to a larger extent regarding
FAC, gait velocity, RMI, and MI (p < 0.025). During follow-up, the
superior effect in favor of the experimental group persisted for the FAC
and the MI, whereas gait velocity and the RMI did not differ. Muscle
tone did not differ between the two groups at any time (Table 4).

At the end of the study, seven experimental group patients and one
control group patient regained the ability to climb up and down at least
one flight of stairs independently (FAC score of 5). At follow-up, 11
experimental group patients and 6 control group patients had achieved an
FAC score of 5.

[FIGURE 2 OMITTED]

DISCUSSION

The clinical potential of the G-EO System that enabled the
repetitive practice of floor walking and stair climbing became apparent.
The experimental group patients improved their gait and stair climbing
ability to a significantly larger extent and the superior effect
persisted at follow-up. Any definite conclusions on the machine's
effectiveness in patients with subacute stroke are not yet warranted.
The major limitation was the missing randomization of the patients
because the two groups were treated consecutively.

Pretests showed that very severely affected patients with stroke,
completely unable to walk on the floor or requiring the physical help of
two persons (corresponding to a FAC of score 0), were less suitable
candidates. Poor balance and knee control limited their ability to climb
stairs up or down; furthermore, they tended to feel un-secure when their
feet were lifted too far from the ground. We set the inclusion criteria
to an FAC score of [greater than or equal to] 1 accordingly. Other
potential treatment-related risks were joint arthritis, cardiovascular
overexertion, and pressure sores in the groin. One experimental group
subject interrupted training because of knee arthritis after 2 weeks.

[FIGURE 3 OMITTED]

Gait and stair-climbing ability improved to a significantly larger
extent in the experimental group compared with the control group. At the
end of the 4-week intervention, seven experimental group patients but
only one control group patient had reached an FAC score of 5, indicating
both an independent gait and the ability to climb up and down at least
one flight of stairs. At follow-up, the superior gait and stair climbing
ability in the experimental group persisted.

Both groups, the absolute treatment times, and the remaining
rehabilitation program were comparable at study onset. Accordingly, the
higher gait and stair climbing intensity probably explained the final
superior result in the experimental group. The mean distance covered per
60 min session was six times higher in the experimental group. For stair
climbing, the experimental group patients even climbed 20 times more
steps per session. This difference is explained by the G-EO
System's characteristics enabling the repetitive practice of stair
climbing, but also by the fact that the experimental group patients and
their therapists practiced stair climbing within their 30 min PT session
as intensively as the control group patients within their 60 min PT
session. The combined therapy of the experimental group resulted in a
faster recuperation of gait, thus reducing the effort for the patients
and their therapists on real stairs.

One may argue that the practice of stair climbing is premature in
nonambulatory patients with stroke. First, it is commonly applied within
the Bobath technique to promote a most physiological stance and swing
phase [32]. Second, the knowledge transfer from one motor task to
another seems limited [33]. Third, short bouts of stair climbing
provided a strong cardiovascular training effect in sedentary young
women [34].

The major limitations of the study are obvious: the two groups were
not randomized, but rather assigned consecutively, and the patient
number (n = 30) was small. In addition, a very experienced therapist
provided the robot therapy, and blind assessment could not be fully
guaranteed because the raters were team members. The FAC was
video-recorded and rated by an external colleague.

CONCLUSIONS

The novel gait G-EO System robot offers nonambulatory patients with
stroke the ability to repetitively practice both simulated floor walking
and stair climbing. Because of the higher training intensity, the
experimental group patients reached a superior gait and stair climbing
ability after the intervention and at follow-up. At present, no definite
conclusions on the G-EO System's effectiveness are warranted and a
robust randomized controlled trial should follow.

Gait and stair climbing restoration is pivotal in neurological
rehabilitation. A novel gait robot helped to increase training
intensity, which is regarded as essential for a successful outcome. A
harness-secured patient stands on two footplates, whose movements are
fully programmable, so that he or she can practise gait and stair
climbing repetitively, up to several hundred steps and stairs per
session. A controlled trial with 30 subacute stroke patients revealed a
superior gait and stair climbing ability in the experimental group
compared with the control group. More studies must follow to better
understand the robot's promising potential.

ACKNOWLEDGMENTS

Author Contributions:

Study design: A. Waldner.

Principal investigator: S. Hesse.

Patient treatment: C. Tomelleri, A. Bardeleben.

Assessment: C. Werner.

Data management: C. Werner.

Drafting of manuscript: S. Hesse, C. Werner.

Technical support: C. Tomelleri.

Financial Contributions: Reha Technology AG holds the international
patent for the G-EO System. Drs. Hesse and Waldner are shareholders of
the company, but the company had no involvement in the study design; the
collection, analysis, and interpretation of the data; the writing of the
article; or the decision to submit the article for publication.

Funding/Support: This material was unfunded at the time of
manuscript preparation.

Institutional Review: Participants provided written consent in the
study approved by the local ethical committee.

Participant Follow-Up: The authors do not plan to inform the
participants of the publication of this study.